This invention relates generally to electrical wiring devices and more particularly to an apparatus which is employed in conjunction with a bearing assembly utilized for preventing the twisting or coiling of an electrical cord.
Twisted wires have often plagued operators of hand-held appliances and tools. For example, a device is plugged into a conventional outlet and, during operation, the power cord becomes twisted. As a result, the plug might be pulled out of the socket, or, if the cord is old and brittle, it might break. Thus, the problems associated with twisted power cords are apparent.
The prior art is replete with many patents which relate to the problem of avoiding the twisting or coiling of various wires. Many of such patents utilize a conductive bearing assembly to allow rotation of one wire with respect to the other while other patents utilize a conductive bearing assembly to prevent the twisting of an input wire with respect to an output wire. Essentially, reference is made to U.S. Pat. No. 4,592,605 entitled "Apparatus for Preventing the Twisting of an Electrical Cord or Cable" issued on Jun. 3, 1986 to Albert W. Kapler of Edison, N.J. See also U.S. Pat. No. 4,708,658 entitled "Apparatus for Eliminating Noise in Conductive Bearing Electrical Connectors", issued on Nov. 24, 1987 to Albert W. Kapler and Joseph A. Kapler, an inventor herein. The above-noted patents were concerned with the twisting or coiling of telephone wires. These inventions could also be adapted to prevent the twisting of other types of wires, such as electrical line cords which are conventionally employed in conjunction with a typical power line.
Thus, a twisted cord causes the plug to be pulled out of the socket or otherwise rotated which will cause the cord to break. It is therefore desirable to provide a device which will rotatably connect an electrical cord to a convenience outlet or rotatably connect two parts of an electrical cord, to permit manipulation of the device to which the cord is connected without twisting of the cord. One can, of course, understand that in order to provide such a device suitable for domestic use, the device must be simple, reliable and fabricated at low cost.
The prior art is replete with many devices which attempt to solve the problem. For examples of typical prior art, reference is made to U.S. Pat. No. 913,831 patented Mar. 2, 1909 and entitled "Swivel for Electrical Appliances". Essentially, the patent shows a rotatable or swivel assembly which is used in conjunction with an electrical appliance, such as a curling iron. The device employs ball bearings in order to provide rotation of an input wire with respect to an output wire to thereby prevent twisting. Similarly attention is directed to U.S. Pat. No. 1,649,276 issued on Nov. 15, 1927 to A. G. Adam entitled "Electrical Swivel Connection". This patent shows a mechanism for relieving electrical conductors within the cable from tensile strain. In that patent the strain relieving mechanism disclosed includes a boss 19 which is provided on the electrical cable such that it engages a cap nut 11. In any event, that patent also shows the use of conductive bearings to prevent twisting of the electrical cord. Reference is also made to U.S. Pat. No. 1,837,890, U.S. Pat. No. 2,181,145, U.S. Pat. No. 2,328,212, U.S. Pat. No. 2,502,252, U.S. Pat. No. 3,123,421 and U.S. Pat. No. 3,581,267. Reference is also made to foreign patents as follows: Swiss Pat. No. 272,686, Italian Pat. No. 562,438, Italian Pat. No. 700,847, Italian Pat. No. 543,314 and Italian Pat. No. 531,432. Essentially, all of the above noted patents relate to various devices including ball bearings for preventing the twisting of one electrical cord with respect to another in order to solve the above-described problems.
While the aforementioned references teach the use of conductive bearing assemblies to eliminate torsional stress, they do not address problems as for example the tensile strain produced on such connectors or cables, which frequently occurs at the same time they are subjected to rotation. The tensile load pulls the wires apart at their electrical connections, thereby disconnecting the appliance.
Furthermore, a problem arises when the mechanism can follow the motions of the cable in a rapid manner. The prior art devices, while attempting to solve the general problem of free rotation, exhibit these difficulties in that the mechanisms employed created extensive tensile strains on the cables while being relatively slow so as not being able to follow cable motion.
Other considerations include a device which is capable of handling commercially practicable amounts of current as supplied through a conventional wall socket to a hand tool. The device should be extremely simple and economical to manufacture and use.
Therefore, it is an object of the present invention to provide an electrical connector which reduces a torsional load on two connected cables and removes the tensile load at the connection thereof.
Another object of the present invention is to provide a means for transmitting tensile loads from the electrical connections of the cables to the apparatus. Still, another object is to provide a low friction device which allows one cable end to follow the motion of the other end freely and rapidly.